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Emergency BROWN-OUT AGAIN!

Discussion in 'Dumaguete City' started by Glendazumba, Aug 30, 2020.

  1. djfinn6230

    djfinn6230 DI Senior Member

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    As I would expect, Honda generators are (claimed to be) pure sine wave.
    From the Honda site:

    "Why does Honda do it better? Our inverter generators (see the portable range) provide 'pure sine wave' power. Other cheaper generators use 'square sine wave' or modified sine waves. The image below illustrates this."

    [​IMG][​IMG]
     
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  2. NowandThen

    NowandThen DI Member

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    Good question. Maybe Grandpaniak, Philpots or Show Pony can enlighten us.

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  3. djfinn6230

    djfinn6230 DI Senior Member

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    Sorry, it wasn’t actually a question. It is actually a form of ‘statement’ quoted by Honda. I tend to believe them, for one thing because it is so easily checked. Probably some cheaper inverter gens on the market are square waves or modified sine as they need fewer components but are not desirable for a number of reasons. Most of us still use electromechanical alternator constructions which generally produce sine waves under normal load but inverters will probably replace them in the future.


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  4. NowandThen

    NowandThen DI Member

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    Sorry

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  5. Philpots

    Philpots DI Senior Member

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    Not'as fast" rpm, because if that happened the frequency would change, 60 hz, All that changes is the "power" being applied to the alternator to turn it against the added load. A more throaty roar.
     
  6. Philpots

    Philpots DI Senior Member

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    Basically, the number of poles (the armature) being spun through a magnetic field (the field coils) changes the "shape"of the generated wave.
     
  7. Show Pony

    Show Pony DI Forum Patron Highly Rated Poster Showcase Reviewer

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    What you said is true for a conventional generator.
    With the inverter type generator is different. The rotor/stator will produce AC at a frequency that varies with the speed of the gasoline motor. The AC gets rectified to DC. The DC gets chopped up (pulse width modulated) into 60 Hz AC output.
    The overall result is if your load is only 1 hp the gas engine will only turn as fast as is required to produce 1 hp. If the load increase to say 1.5 hp the gas engine will speed up to the level required to produce 1.5 hp.
    There is some pretty slick (and cool) stuff out there nowadays.
     
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  8. djfinn6230

    djfinn6230 DI Senior Member

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    Actually it is not like that. Here is a simplified inverter generator (conceptual) circuit:
    [​IMG]
    The 3-PH alternator is rectified to DC anyway so RPM, number of poles etc. has nothing to do with the generated output wave. In fact, the output current is sensed and feeds back to the RPM control, only turning the alternator as fast as output power demands. This saves a lot of gas and also lets it run more quietly. The output frequency is determined by the switching frequency of the power transistors above (i.e. 50/60 Hz, which can sometimes even be electronically selected by the user). The PWM control above is usually an IC circuit; you can see that it senses the output voltage. As the generator load increases, the voltage decreases, so, the voltage is fed back to the PWM which tells the base drive circuit to provide wider pulses to the bases of the transistors; this in turn provides more energy that brings the output voltage back up again. This is the standard inverter circuit (DC to AC) configuration found in other products like switch mode power supplies. So, it senses both output current, to control alternator RPM as needed for current load, and output voltage, to ensure sufficient energy is provided to the inverter to keep the output voltage constant. The actual shape of the generated wave is defined in the above circuit section labeled FILTER. It can be cheap or expensive depending on the components used; the transistors switch on and off providing a square wave which must be shaped into something sinusoidal to allow appliances to work properly.

    End of EE 101 lesson for today. A quiz will be given next session (LOL).
     
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  9. Rye83

    Rye83 with pastrami Secured Account Highly Rated Poster SC Connoisseur Veteran Army

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    I completely stopped using mine because of the noise and infrequent use (which requires additional maintenance). I only keep it around in case of another typhoon or earthquake. I'll fix it when I need it.. or just buy another.
     
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  10. Mark K

    Mark K DI Member

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    1.5L of petrol (more or less) per hour, plus the cost of purchasing and maintenance. Seems an awful lot of expense just to have a some power. Wouldn't it be easier just to find somewhere with a nice breeze/ somewhere to take a dip and just read a book and have a beer? :smile:
     
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